1. Field of the Invention
The present invention relates to optical systems. More specifically, the present invention relates to beam steering optical arrangements.
2. Description of the Related Art
For many applications, there is a need for a compact, high performance optical arrangement with a steerable beam. Such applications include astronomy, medicine, weaponry and numerous other commercial, industrial and military applications. For such applications, beam steering is typically accomplished with a gimbaled arrangement. Typically, a lens or optical element is mounted to a gimbal. The gimbal is free to rotate about one to three axes. Hence, with a motor, the optical arrangement may be directed to a desired roll angle to steer the beam as necessary.
Unfortunately, the gimbal and the actuators for same add to the cost and complexity of the system. In addition, for certain applications, it is desirable to effect beam steering with a more compact arrangement than would be afforded by a typical gimbaled arrangement.
Moreover, in many optical systems, there is a need to correct for optical aberrations. Such aberrations may result from distortion in an input aperture or from some other element in the optical train.
Hence, a need exists in the art for a compact, efficient, high performance optical arrangement with a mechanism for effecting beam steering and aberration correction.
The need in the art is addressed by the steerable optical arrangement of the present invention. The inventive arrangement includes a first prism mounted for rotation about an optical axis and a second prism mounted for rotation about the optical axis. In accordance with the inventive teachings, the first prism and/or the second prism have at least one surface contoured to correct for optical aberration.
In the illustrative embodiment, the first and second prisms are Risley prisms. In addition, the illustrative implementation includes a first motor arrangement for rotating the first prism about the optical axis and a second motor arrangement for rotating the second prism about the optical axis. A controller is provided for activating the first and second motors to steer the beam at an angle xcfx86 and nod the beam at an angle xcex8.
At least one surface of at least one prism is contoured to correct for astigmatism, coma, trefoil, oblique and/or focus. The contour is effected by laser etching, micro-machining or optical thin-film coating of the prisms in the manner disclosed herein.